The program starts from the GUI when enduser make the input. Calculated values from which to extract data from a data base and then coming back to the enduser to display.
From the GUI application running on enduser data entry. The program will Calculated values From which to retrieve data from the data base and return the display to the enduser.
The program started work at the GUI when enduser the input program will make the calculation from where to retrieve data from the data base and come back around to show the difference Enduser.